A quantum cryptography apparatus and system includes a photon emitter, a photon receiver, a first photodetector, a second photodetector, a first polarization optic, and a second polarization optic. The photon emitter is configured to emit a photon at a wavelength. The photon receiver is coupled to the photon emitter by at least one quantum channel. The photon receiver includes the first polarization optic configured to output the emitted photon in a polarization state. The first photodetector is configured to detect the emitted photon from the output of the first polarization optic. The second photodetector is configured to detect a backflash from the first photodetector. The second polarization optic is between the first photodetector and the second photodetector. The second photodetector and the second polarization optic are configured to internally calibrate the photon receiver.
Legal claims defining the scope of protection, as filed with the USPTO.
2. The method of claim 1, wherein the calibrating comprises calibrating the photon receiver based on an information leakage percentage of the quantum cryptography apparatus.
3. The method of claim 1, wherein the calibrating comprises calibrating the photon receiver based on a quantum bit error rate of the quantum cryptography apparatus.
4. The method of claim 1, further comprising triggering an alarm based on the polarization dependence of the backflash.
5. The method of claim 1, further comprising deterring subsequent measurement of the backflash based on the polarization dependence of the backflash.
6. The method of claim 1, further comprising decrypting a quantum key distribution between the photon emitter and the photon receiver.
7. The method of claim 1, further comprising transferring the emitted photon by at least one quantum channel to the photon receiver.
10. The method of claim 1, wherein the receiving comprises receiving the emitted photon through a first polarization optic configured to output the emitted photon in the polarization state.
11. The method of claim 1, wherein the receiving comprises receiving the emitted photon with a first photodetector.
12. The method of claim 1, wherein the detecting comprises detecting the backflash from a first photodetector with a second photodetector.
13. The method of claim 1, wherein the characterizing comprises characterizing the polarization dependence of the backflash through a second polarization optic.
15. The method of claim 14, further comprising triggering an alarm based on the polarization dependence of the backflash.
16. The method of claim 15, wherein the triggering the alarm is based on an information leakage percentage, a quantum bit error rate, or both of the quantum key distribution system.
17. The method of claim 15, further comprising deterring subsequent measurement of the backflash based on the alarm.
18. The method of claim 17, wherein the deterring subsequent measurement of the backflash comprises implementing an optical isolator, an optical circulator, an optical modulator, an optical filter, an optical switch, an optical router, or a combination thereof.
19. The method of claim 18, wherein the implementing comprises activing the optical circulator to siphon off the backflash.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 19, 2020
June 18, 2024
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.